bs en12715
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BRITISH STANDARD BS EN12715:2000
The European Standard EN 12715:2000 has the status of aBritish Standard
ICS 93.020
NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW
Execution of specialgeotechnical work Grouting
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This British Standard, havingbeen prepared under thedirection of the SectorCommittee for Building and CivilEngineering, was published underthe authority of the StandardsCommittee and comes into effecton 15 September 2000
BSI 09-2000
ISBN 0 580 34933 0
BS EN 12715:2000
Amendments issued since publication
Amd. No. Date Comments
National foreword
This British Standard is the official English language version of EN 12715:2000.
The UK participation in its preparation was entrusted by Technical CommitteeB/526, Geotechnics, to Subcommittee B/526/4, Strengthened reinforced soils andother fills, which has the responsibility to:
aid enquirers to understand the text;
present to the responsible European committee any enquiries on theinterpretation, or proposals for change, and keep the UK interests informed;
monitor related international and European developments and promulgatethem in the UK.
A list of organizations represented on this subcommittee can be obtained on requestto its secretary.
Cross-references
The British Standards which implement international or European publicationsreferred to in this document may be found in the BSI Standards Catalogue under thesection entitled International Standards Correspondence Index, or by using theFind facility of the BSI Standards Electronic Catalogue.
A British Standard does not purport to include all the necessary provisions of acontract. Users of British Standards are responsible for their correct application.
Compliance with a British Standard does not of itself confer immunityfrom legal obligations.
Summary of pages
This document comprises a front cover, an inside front cover, the EN title page,pages 2 to 52, an inside back cover and a back cover.
The BSI copyright notice displayed in this document indicates when the documentwas last issued.
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EUROPEAN STANDARD
NORME EUROPENNE
EUROPISCHE NORM
EN 12715
July 2000
ICS 93.020
English version
Execution of special geotechnical work Grouting
Excution des travaux gotechniques spciaux Injection Ausfhrung von besonderen geotechnischen Arbeiten(Spezialtiefbau) Injektionen
This European Standard was approved by CEN on 9 June 2000.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the Central Secretariat or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the officialversions.
CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATIONC O M I T E U R OP E N D E N O R M A LI S A T I O NEUR O P IS C HES KOM I TE E FR NOR M UNG
Central Secretariat: rue de Stassart, 36 B-1050 Brussels
2000 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Members.
Ref. No. EN 12715:2000 E
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Page 2EN 12715:2000
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ContentsPage
Foreword........................................................................................................................................................... 31 Scope.................................................................................................................................................... 42 Normative references ......................................................................................................................... 43 Definitions and symbols..................................................................................................................... 53.1 Definitions............................................................................................................................................ 53.2 Symbols and units .............................................................................................................................. 74 Information needed............................................................................................................................. 75 Site investigation ................................................................................................................................ 85.1 General ................................................................................................................................................. 85.2 Permeability testing ............................................................................................................................ 95.3 Field grouting trials and grouting tests .......................................................................................... 106 Materials and products..................................................................................................................... 106.1 General ............................................................................................................................................... 106.2 Grout materials.................................................................................................................................. 106.3 Grouts................................................................................................................................................. 126.4 Sampling and testing........................................................................................................................ 147 Design considerations...................................................................................................................... 147.1 General ............................................................................................................................................... 147.2 Design basis and objectives............................................................................................................ 147.3 Grouting principles and methods ................................................................................................... 157.4 Grout................................................................................................................................................... 177.5 Grout placement................................................................................................................................ 207.6 Monitoring and control criteria........................................................................................................ 228 Execution ........................................................................................................................................... 238.1 General ............................................................................................................................................... 238.2 Drilling ................................................................................................................................................ 238.3 Grout preparation.............................................................................................................................. 248.4 Grout placement................................................................................................................................ 258.5 Grouting sequences ......................................................................................................................... 279 Execution supervision and control ................................................................................................. 279.1 General ............................................................................................................................................... 279.2 Supervision........................................................................................................................................ 279.3 Monitoring and control ..................................................................................................................... 2810 Works documentation ...................................................................................................................... 3011 Special aspects (environment, site safety) .................................................................................... 3111.1 Personnel safety ............................................................................................................................... 3211.2 Environmental protection................................................................................................................. 32Annex A (informative) Measurement of grout parameters ......................................................................... 34Annex B (informative) Glossary .................................................................................................................... 38Annex C (informative) Degree of obligation of the provisions .................................................................. 47Bibliography ................................................................................................................................................... 52
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Page 3EN 12715:2000
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Foreword
This European Standard has been prepared by Technical Committee CEN/TC 188, Execution of specialgeotechnical works, the Secretariat of which is held by AFNOR.
This European Standard shall be given the status of a national standard, either by publication of an identical textor by endorsement, at the latest by January 2001, and conflicting national standards shall be withdrawn at thelatest by January 2001.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the followingcountries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark,Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain,Sweden, Switzerland and the United Kingdom.
This standard has been prepared by the Working Group (WG 6) of the CEN/TC 288. The general remit ofTC/288 is the standardization of the execution procedures for geotechnical works (including testing and controlmethods) and of the required material properties. WG 6 has been charged with the subject area of grouting,including compaction grouting.
The document has been prepared to stand alongside ENV 1997-1: EUROCODE 7: Geotechnics, GeotechnicalDesign, General Rules. This standard expands on design only where necessary, but provides full coverage ofthe construction and supervision requirements.
It has been drafted by a working group comprising delegates from 9 countries and against a background ofmore than ten pre-existing grouting standards and codes of practice, both national and international. In view ofthe different construction methods used internationally and the respective experience, it may be necessary tosupplement this standard, or parts of it, by National Application Documents to cater for specific or localsituations.
The annexes A, B and C are informative.
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Page 4EN 12715:2000
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1 Scope
This standard is applicable to the execution, testing and monitoring of geotechnical grouting work. Specificaspects concerning design are provided since ENV 1997-4 has been abandoned.
Grouting for geotechnical purposes (geotechnical grouting) is a process in which the remote placement of apumpable material in the ground is indirectly controlled by adjusting its rheological characteristics and by themanipulation of the placement parameters (pressure, volume and the flow rate).
The following principles and methods of geotechnical grouting are covered by this standard:
displacement grouting (compaction grouting, hydraulic fracturing);
grouting without displacement of the host material (permeation, fissure grouting, bulk filling).
Specialized grouting activities, generally associated with structural and/or emergency works, are not covered bythis standard.
2 Normative references
This European Standard incorporates, by dated or undated reference, provisions from other publications. Thesenormative references are cited in the appropriate places in the text and the publications are listed hereafter. Fordated references, subsequent amendments to or revisions of any of these publications apply to this EuropeanStandard only when incorporated in it by amendment or revision. For undated references the latest edition of thepublication referred to applies.
EN 196-1, Methods of testing cement Part 1: Determination of strength.
EN 196-2, Methods of testing cement Part 2: Chemical analysis of cement.
EN 196-3, Methods of testing cement Part 3: Determination of setting time and soundness.
ENV 196-4, Methods of testing cement Part 4: Quantitative determination of constituents.
EN 196-5, Methods of testing cement Part 5: Pozzdanicity test for pozzolanic cement.
prEN 196-8:1997, Methods of testing cement Part 8: Determination of heat of hydration.
prEN 196-9:1997, Methods of testing cement Part 9: Determination of heat of hydration Semi-adiabaticmethod.
prEN 197-1:2000, Cement Part 1: Composition, specifications and conformity criteria for common cements.
prEN 197-2:2000, Cement Part 2: Conformity evaluation.
ENV 451, Methods of testing fly ash.
EN 480-1, Admixtures for concrete, mortar and grout Test methods Part 1: Reference concrete andreference mortar for testing.
EN 480-2, Admixtures for concrete, mortar and grout Test methods Part 2: Determination of setting time.
prEN 480-3:1991, Admixtures for concrete, mortar and grout Test methods Part 3: Determination ofshrinkage and expansion.
EN 480-4, Admixtures for concrete, mortar and grout Test methods Part 4: Determination of bleeding ofconcrete.
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EN 480-5, Admixtures for concrete, mortar and grout Test methods Part 5: Determination of capillaryabsorption.
EN 480-6, Admixtures for concrete, mortar and grout Test methods Part 6: Infrared analysis.
prEN 480-7:1991, Admixtures for concrete, mortar and grout Test methods Part 7: Determination of thedensity of liquid admixtures.
EN 480-8, Admixtures for concrete, mortar and grout Test methods Part 8: Determination of theconventional dry material content.
prEN 480-9:1991, Admixtures for concrete, mortar and grout Test methods Part 9: Determination of the pHvalue.
EN 480-10, Admixtures for concrete, mortar and grout Test methods Part 10: Determination of water solublechloride content.
EN 480-11, Admixtures for concrete, mortar and grout Test methods Part 11: Determination of air voidcharacteristics in hardened concrete.
EN 480-12, Admixtures for concrete, mortar and grout Test methods Part 12: Determination of the alkalicontent of admixtures.
prEN 934-1:1998, Admixtures for concrete, mortar and grout General definitions and general requirements forall types of admixtures.
prEN 934-3:1998, Admixtures for concrete, mortar and grout Part 3: Admixtures for masonry mortar Definitions, requirements and conformity.
EN 934-4, Admixtures for concrete, mortar and grout Part 4: Admixtures for grout for prestressing tendons Definitions, requirements and conformity.
EN 934-6, Admixtures for concrete, mortar and grout Part 6: Sampling, quality control, evaluation ofconformity and marking and labelling.
ENV 1997-1:1994, EUROCODE 7: Geotechnical design Part 1: General rules.
3 Definitions and symbols
3.1 Definitions
The definitions given in this chapter cover only the most important terms involved in geotechnical grouting.Further definitions are given in the glossary in annex B.
3.1.1 fr: injection de comblementbulk filling de: Hohlraumverfllungbulk filling is the placement of grout with a high particulate content to fill substantial voids
3.1.2 fr: injection solidecompaction grouting de: Verdichtungsinjektion (Kompaktionsinjektion)displacement grouting method which aims at forcing a mortar of high internal friction into the soil to compact itwithout fracturing it
3.1.3 fr: injection de contactcontact grouting de: Kontaktinjektioninjection of grout into the interface between man-made structures and the ground
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3.1.4 fr: injection avec dplacement des terrainsdisplacement grouting de: Verdrngungsinjektioninjection of grout into a host medium in such a manner as to deform, compress, or displace the ground
3.1.5 fr: pression effectiveeffective pressure de: wirksamer Druckactual grout pressure acting in the ground
3.1.6 fr: injection de fissurefissure grouting de: Kluftinjektioninjection of grout into fissures, joints, fractures and discontinuities, particularly in rock
3.1.7 fr: injection gravitairegravity grouting de: drucklose Verfllunggrouting under no applied pressure other than the height of grout fluid. Sometimes referred to as tremie grouting
3.1.8 fr: coulisgrout de: Injektionsgutpumpable material (suspension, solution, emulsion or mortar), injected into soil or rock, which stiffens and setswith time
3.1.9 fr: pression dinjectiongrouting pressure de: Injektionsdruckpressure applied during the grouting process and measured at defined locations (usually at the pump or theborehole collar)
3.1.10 fr: fracturation hydraulique (injection de claquage)hydraulic fracturing (hydraulic fracture, de: Hydraulische Rissbildung (Claquage)claquage grouting)fracturing of a ground initiated by the injection of water or grout under a pressure in excess of the local tensilestrength and confining pressure; also called hydrofracturing, hydrosplitting, hydrojacking or claquage
3.1.11 fr: injection de pntrationpenetration grouting de: Eindringinjektiongrout injection of joints or fractures in rock, or pore spaces in soil, without displacing the ground. The termincludes permeation (impregnation), fissure and contact grouting
3.1.12 fr: injection dimprgnationpermeation (impregnation) grouting de: Poreninjektion (Imprgntion durch
Porenverfllung)replacement of interstitial water or gas of a porous medium with a grout at injection pressures low enough toprevent displacement
3.1.13 fr: injection sans dplacement des terrainsnon-displacement grouting de: Verdrngungsfreie Injektion (Injektion ohne
Baugrundverdrngung)substitution of the natural interstitial fluid in the accessible existing voids of the ground by a grout or mortarwithout any significant displacement of the ground. The term includes penetration grouting and bulk filling
3.1.14 fr: suspension stablestable suspension de: stabile Suspensionstable suspensions exhibit in 2 hours less than 5 per cent bleeding of clear water at the top of a 1 000 mlcylinder with an internal diameter of 60 mm at a temperature of 20 C
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3.2 Symbols and units
The following symbols and units are used in this standard.
Symbols Denomination Unit
T Temperature [C]V Volume injected [m3]P Injection pressure [Pa]Q Injection or flow rate [m3/s] or [l/s]k Intrinsic (absolute) permeability1) [m2]K Coefficient of hydraulic conductivity [m/s]i Hydraulic gradient [dimensionless]
d10, d15 Largest particle size of the smallest 10, 15 % of grout [mm]D85, D90 Largest grain size of the smallest 85, 90 % of the medium
t Setting time [s]c Compressive strength [Pa]
f Shear strength
Normal stress [Pa]
Shear stress
Strain [dimensionless]
Shear rate [s-1]
app Viscosity (apparent) [Pas], [kg/ms] (dynamic) [Pas] (kinematic) [m2/s]c Cohesion [Pa]o Yield shear stress [Pa]
Density [kg/m3]
Specific or unit weight [kN/m3]
tM Outflow time (Marsh) [s]R Action radius [m]
1 Pa = 1 N/m2 = 10-5 bar1) It is common practice in geotechnical engineering to use k for hydraulic conductivity. Nevertheless, this refers tothe parameters generally used in rock and fluid mechanics.
4 Information needed
4.1 All information relevant to the execution of the grouting works should be provided with the workspecifications.
4.2 The following technical information shall be available on site before the commencement of the works:
site conditions and limitations, e.g. size, gradients, access;
working restrictions, including any environmental, legal or statutory restrictions;
any underground contamination or hazard which could affect the method of execution or the safety of theworking environment;
design and specifications for the works.
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4.3 The following technical information should be available on site before the commencement of the works:
geological and geotechnical conditions (see chapter 5);
the co-ordinate locations of the site with respect to the national grid;
existence, location and conditions of any adjacent structures, e.g. buildings, roads, utilities or services,underground structures and their foundations;
any concurrent or subsequent activities which could affect the works (e.g. groundwater extraction orrecharge, tunnelling, other deep excavations);
any previous experience with grouting or other underground works on or adjacent to the site, or relevantexperience in the execution of comparable works under similar conditions;
any information relevant for the production of drawings and method statements (where required);
any additional requirements for the supervision, monitoring or testing of the works.
4.4 The following aspects shall be established before the commencement of the works and shall be availablein written form on site:
the requirement, and assignment, for any survey of the condition of adjacent structures, roads, services,etc. to be carried out prior to, during and after the works;
specific procedures and criteria for the verification, control and acceptance of the grouting works;
the clear division of tasks with respect to the design, execution, interpretation of results and approval of theworks.
5 Site investigation
5.1 General
5.1.1 The general requirements for site investigation are contained in ENV 1997-1:1994, chapters 3 and 7and the relevant national documents.
5.1.2 For design purposes, the site investigations should:
provide a comprehensive geotechnical report;
establish the ground susceptibility to grout;
furnish a basis for selecting the grout types.
5.1.3 For the execution, the ground investigation report should contain the following specific information:
the relevant physical and chemical characteristics of the ground;
the ground level at investigation and testing locations relative to a recognized datum;
the location, founding level and condition of existing or envisaged structures;
the presence of any anisotropies or permeable horizons which could influence the grouting works;
the orientation, frequency, and width of rock joints and the composition and nature of any infill material;
the location and nature of filled or open cavities;
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the presence of obstructions that require special drilling and grouting methods or equipment;
the presence and characteristics of ground that is likely to loosen, soften or become unstable, dissolve,collapse or swell as a result of drilling or grouting;
the groundwater levels and gradients and their variation with time;
strata with high groundwater velocities and permeabilities;
the temperature, chemical composition, organic and bacteriological content of the groundwater or ground, ifproblems are expected.
5.1.4 The geological and geometrical model, and the void structure and its anticipated evolution should bedescribed in the investigation report. The precision and limits of the model should be highlighted.
5.1.5 Where relevant, the following specific drilling information should be recorded:
location and cause of core losses;
unstable zones and stabilization measures taken;
water level at the beginning and end of a run, zones of water loss and gain, measurements of return water,water colour and changes in colour;
action of the drill rig (jerky, rough, smooth, steady motion);
recording of drill parameters in the case of destructive boreholes;
rate of advance.
5.1.6 Special care shall be taken when investigating for injections in high stress regions and in pollutedground:
for injections in high stress regions, the in situ state of stress shall be investigated before designing agrouting project;
for the injection of organic gels into polluted soils, a bacteriological investigation of the groundwater andground shall be carried out.
5.1.7 Site investigation boreholes shall be suitably backfilled when no longer required.
5.2 Permeability testing
5.2.1 The hydraulic conductivity of the ground may be:
determined from in situ permeability tests or large scale pumping tests;
estimated from laboratory tests on samples of undisturbed soil or recompacted soil;
estimated from the particle size distribution of the soil, and/or density of the ground.
5.2.2 Suitable correlations with actual field permeabilities should be established.
5.2.3 Each site investigation hole in rock should be tested to determine the water take and to identify thewater bearing or open zones in the hole. The hole should be either tested as it is drilled or tested by the use ofpackers after drilling is completed.
5.2.4 Special care shall be taken to isolate artesian zones before testing.
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5.2.5 Lugeon tests are used in rock to obtain a general impression of the transmissivity of the ground. Theydo not necessarily provide a reliable correlation with the absorption of a specific grout.
5.3 Field grouting trials and grouting tests
5.3.1 Field grouting trials are executed in order to define or validate a grouting method. Field grouting trialsshould be considered as part of the initial site investigation. They should be conducted during the final designphase, or the first part of the construction phase if they did not form part of the site investigation. They should beexecuted where initial investigations and local or comparable experience is insufficient to support or justify theeffectiveness of the grouting project. The trials should provide information on borehole spacing, groutingpressure and grout take and type.
5.3.2 Grouting trials shall be planned and executed in close collaboration with the designer of the finalgrouting program.
5.3.3 The limit criteria for the properties of the proposed grout should be established on the basis ofexperience gained during the trial grouting.
5.3.4 Detailed records shall be kept of each operation performed during the grouting trials.
5.3.5 An indication of in situ conditions may be obtained by permeating reconstituted soil samples with trialgrouts, under laboratory conditions. Permeability measurements made before and after grouting the samplemay provide indicative information which will facilitate decisions on the frequency of injection points, the desiredproperties of the grout mix, and the required grout volume.
6 Materials and products
6.1 General
6.1.1 All grout components and grouts shall comply with the specifications for the works and the relevantEN or national standards.
6.1.2 The compatibility of all grout constituents shall be evaluated. Similarly, an assessment shall be made ofthe possible interaction between the grout and the ground.
6.1.3 Once established, the sources of grout materials shall not be changed without prior complianceverification or testing.
6.1.4 Materials that do not meet agreed quality standards shall promptly be removed from the site.
6.2 Grout materials
6.2.1 Hydraulic binders and cements
6.2.1.1 Hydraulic binders include all cements and similar products used in water suspension for makinggrouts.
6.2.1.2 Microfine (ultra-fine) hydraulic binders or cements are characterized by a particle size d95 of lessthan 20 m.
6.2.1.3 The granulometric curve, especially of the microfine products used, shall be known.
6.2.1.4 When selecting the type of hydraulic binder for grout, its grain size distribution should beconsidered in relation to the dimensions of the fissures or voids of the ground to be treated.
6.2.1.5 Cements are subject to prEN 197-1:2000 and prEN 197-2:2000. Methods for testing of cements aresubject to EN 196. Properties and methods different from those mentioned in those standards and specific togrouting are subject of this standard.
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6.2.2 Clay materials
6.2.2.1 Natural clays, activated or modified bentonites can be added to cement based grouts in order toreduce bleeding and filtration under pressure, to vary the viscosity and cohesion (yield) of the grout, or toimprove the pumpability of the grout.
6.2.2.2 The mineralogy, particle size, water content, and Atterberg liquid limit of the clay should be known.
6.2.3 Sands, gravels and fillers
6.2.3.1 Sand and fillers are commonly used in cement grouts or clay suspensions as bulking agents or as ameans of varying the consistency of the grout, its resistance to wash-out, or its mechanical strength anddeformability.
6.2.3.2 Natural sands or gravels may be added to grouts, provided that they do not contain any harmfulcomponents.
6.2.3.3 The granulometry of sands and fillers used in grouts shall be known.
6.2.4 Water
6.2.4.1 Water obtained from natural sources on-site should be tested (particularly for chlorides, sulphatesand organic matter) and approved.
6.2.4.2 Sea water can be used provided that the properties of the grout mix are not impaired.
6.2.5 Chemical products and admixtures
6.2.5.1 Chemical products such as silicates and their reagents, lignin based materials, acrylic or epoxyresins, polyurethanes or others can be used in grouting work subject to compliance with environmentallegislation.
6.2.5.2 The effects of all products and by-products resulting from reaction of the chemical products withother components of the grout or with the surrounding ground shall be considered.
6.2.5.3 Admixtures are organic or inorganic products added in small quantities during the mixing process inorder to modify the properties of the grout and to control grout parameters such as viscosity, setting time,stability, and strength, resistance, cohesion and permeability after placement.
6.2.5.4 Admixtures to grout such as superplasticizers, water retaining agents, air entrainers and others aresubject of Parts 1, 3, 4 and 6 of prEN 934 and prEN 480-1 to 480-12.
6.2.6 Other materials
6.2.6.1 Calcareous or siliceous fillers, pulverized fuel ash (pfa), pozzolans and fly ash from thermal powerplants or any inert or reactive components may be used in grouts, provided that they are chemically compatiblewith each other and satisfy immediate and long term environmental requirements.
6.2.6.2 Methods for testing of fly-ash are subject to ENV 451. Methods different from those mentioned inthat standard and specific to grouting are subject of this standard.
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6.3 Grouts
6.3.1 General
6.3.1.1 Grouts are classified as:
suspensions: either particulate or colloidal suspensions;
solutions: either true or colloidal solutions;
mortars.
particulatecolloidalcolloidaltrue
suspensionssolutions mortars
(small solids)(large molecules)
Figure 1 Grout classification
6.3.1.2 The following intrinsic properties shall be considered when choosing a grout:
rheology (viscosity, cohesion, etc.),setting time, stability;
particle size, if applicable;
strength and durability;
toxicity.
6.3.1.3 The main parameters that define the properties of grouts before and after setting are listed below.
Table 1 Parameters characterizing grout properties
Solutions Suspensions Mortars
Beforesetting
setting time, density, pH,surface tension, pot life, filmtime, gel time, viscosity,cohesion, thixotropy
setting time, density, pH,grain size distribution,viscosity, cohesion, yield,thixotropy, stability, waterretention capacity
setting time, density, pH,grain size distribution,viscosity, workability, waterretention capacity
Aftersetting
hardening after setting, finalstrength, pH, deformability,durability, shrinkage,expansion, shear strength,syneresis (silicate basedsolutions)
hardening time, final strength,deformability, durability,shrinkage, expansion,density, shear strength
hardening time, final strength,deformability, durability,shrinkage, expansion
6.3.2 Suspensions
6.3.2.1 Suspensions are characterized by:
the grain size distribution of the solid particles;
their water/solid ratio;
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the rate of sedimentation and bleeding;
their water retention capacity under pressure filtration;
their rheological properties and behaviour with time.
6.3.2.2 The granulometric curve of microfine suspensions should be determined with a laser granulometeror equally precise instrument.
6.3.2.3 The tendency of suspended solids to flocculate (particularly in microfine suspensions) shall betaken into account.
6.3.2.4 The tendency of solids in suspension to settle in water due to gravity forces, and their tendency tobleed under pressure, shall be considered in relation with the nature and properties of the host medium.
6.3.2.5 Colloidal clay suspensions should be prepared so that the clay particles are thoroughlydeflocculated and hydrated before injecting.
6.3.3 Solutions
6.3.3.1 Some types of silicate grout are not stable with time and their use should be carefully assessed.
6.3.3.2 Organic silicate gels may lead to the proliferation of bacteria in the ground.
6.3.3.3 The effect of syneresis on the properties of the treated ground and on the environment, particularlytheir long term effect, shall be evaluated prior to treatment.
6.3.3.4 The effect of temperature differences on the grout behaviour during production and placement shallbe taken into account.
6.3.3.5 Special attention shall be paid to:
the toxicity of individual resin grout components;
the risk of dilution of the grout mixture in the groundwater leading to prolongation of the setting time or eveninhibition of the chemical reaction;
the toxicity of any substance released into the groundwater if the chemical reaction is not fully achieved ormodified by the host medium.
6.3.3.6 Resins are usually applied under the circumstances given in Table 2.
Table 2 Application of resin grouts
Resin type Ground type Use/Application
Acrylic granular soil
finely fissured rock
Reduction of permeability
Improvement of strength
Polyurethane large voids Foaming to block water inflow (aquareactive resins)
Stabilization or local void filling (two component resins)
Phenolic fine sand and sandygravel
Tightening and consolidation
Epoxy fissured rock Improvement of strength
Reduction of permeability
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6.3.4 Mortars
6.3.4.1 Mortars showing high internal friction are used for compaction grouting or for the filling of voids.Their rheological behaviour is usually determined by slump tests (workability, see Table A.1).
6.3.4.2 Mortars flowing under their own weight are generally used for filling cavities, large cracks, openfissures and voids in granular soils. They shall be stable and their rheological behaviour (similar to suspensions)is usually characterized with suitably selected flow cones.
6.3.4.3 When used for compaction grouting, the mortar should contain a minimum of 15 % of fines passing0,1 mm.
6.4 Sampling and testing
6.4.1 The constituent materials of a grout mix as well as the mix itself shall regularly be sampled and tested toverify compliance with the design requirements.
6.4.2 Standardized testing methods (equipment, boundary conditions, analysis) shall be employed to allowcomparison of the characteristics of the products provided by different suppliers.
6.4.3 In the laboratory, grout characteristics should be tested at an ambient temperature of 20 C.
6.4.4 If the conditions on site differ substantially from the laboratory conditions (especially the temperature)tests shall be conducted under the in situ conditions. The temperature development during testing shall bemonitored.
6.4.5 Table A.1 presents methods for testing the more important grout parameters.
7 Design considerations
7.1 General
7.1.1 The basic standard for the design of grout injections is:
ENV 1997-1:1994, EUROCODE 7: Geotechnical design Part 1: General rules.
7.1.2 This present standard supplements the above document and establishes additional requirements andrecommendations for the planning and implementation of geotechnical grouting applications.
7.2 Design basis and objectives
7.2.1 A flexible approach should be adopted to the design and planning of a grouting application in order toadapt the works to unforeseen ground conditions or variations in the behaviour of the host materials as the workprogresses.
7.2.2 The principal objectives of geotechnical grouting are:
the modification of the hydraulic/hydrogeological characteristics the ground;
the modification of the mechanical properties of the ground;
the filling of natural cavities, mine workings, voids adjacent to structures;
inducing displacement to compensate for ground loss or to stabilize and lift footings, slabs and pavements.
7.2.3 In order to formulate a grouting design, the following information shall be made available:
a definition of the grouting objectives and the control criteria;
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adequate ground information, in particular geological, geotechnical and hydrogeological data (includingwater chemistry) relevant to grouting (see clause 5);
limitations imposed by environmental considerations, the influence of or on adjoining structures (buildingsand foundations) or any other parameters which could affect the choice of grout mix and placementtechnique;
references to other grouting projects executed in the same area or under comparable circumstances.
7.2.4 Based on the site investigation, the grouting trials and the design, the following aspects shall beconsidered and addressed by the working documents:
the shape and volume of the ground to be treated;
the measurable properties to be achieved for the life of the project;
the drilling method and pattern;
the grouting techniques and methods to be applied;
the spacing of injection points;
the sequencing of the injections with respect to time, grout composition and injection point;
permissible grouting limits (injection pressure, flowrate and quantity of grout to be injected);
the grout mix compositions;
the required tests and field controls to be adopted before, during and after grouting;
the instrumentation required for monitoring and data logging.
7.2.5 The following aspects should be considered during grouting:
the reliability and completeness of the ground information available;
the performance required of the grout;
the presence of existing structures and their condition;
changes induced in the in situ state of stress and pore pressures as a result of the grouting work, theexisting groundwater conditions as well as expected post construction conditions;
the toxicity of the grouting products;
the working environment in which the grouting materials have to be stored, mixed and injected;
the availability and reliable supply of grouting materials;
environmental and safety restrictions.
7.3 Grouting principles and methods
7.3.1 General
7.3.1.1 The introduction of grout in a host medium is achieved either with or without displacement of theground. Figure 2 illustrates the various injection methods associated with these two principles.
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principlegrouting
methodinjection
(impregnation)
grouting
displacement displacement
hydraulic compaction
penetration bulk filling
fissure/contactgrouting
bulk filling
subprinciple
fracturingpermeation
with groundwithout ground
Figure 2 Grouting principles and methods
7.3.1.2 The term consolidation grouting is sometimes used to emphasize an improvement in the strength ordeformation characteristics of a soil imparted by the permeation treatment. The aim of consolidation grouting insoils and rock is to improve the ground so that it does not undergo any inadmissible deformation. As this termdoes not refer to a grouting principle or injection method, it will be avoided in the following.
7.3.1.3 The term compensation grouting is used when the objective of grouting is to concurrentlycompensate for ground loss caused by tunnelling or excavation works.
7.3.2 Grouting without ground displacement (non-displacement grouting)
7.3.2.1 Permeation (impregnation) grouting
7.3.2.1.1 Permeation grouting aims at filling the accessible interstices between grains in permeable soils by agrout without destruction of the integrity of the ground. It reduces the permeability of the host material andusually increases the strength and density.
7.3.2.1.2 In order to avoid displacement, permeation grouting shall be carried out at carefully controlledpressures and flow rates.
7.3.2.2 Fissure and contact grouting
7.3.2.2.1 Fissure grouting aims at filling open fissures, fractures or joints in a rock mass with grouts withoutcreating new or opening existing fractures, in order to reduce the permeability and/or increase the strength ofthe grouted mass.
7.3.2.2.2 The frequency, orientation, extent, width, roughness and infilling of the discontinuities shall beknown in order to formulate the design.
7.3.2.3 Bulk filling
7.3.2.3.1 Bulk filling is used for the filling of large natural or man made openings. The term is generallyapplied to the placement of large volumes of grout under gravity or at low pressures.
7.3.2.3.2 If a large volume of cement is placed in an enclosed space, the effect of high local temperaturesand induced stresses shall be taken into account.
7.3.2.3.3 Bulk filling may be followed by a phase of grouting under pressure to fill the remaining voids.
7.3.3 Grouting with ground displacement (Displacement grouting)
7.3.3.1 General considerations
7.3.3.1.1 Displacement grouting refers to the injection of grout under pressure with the deliberate intent ofspatially displacing the host medium. The term includes injection methods such as compaction grouting, and
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hydraulic fracturing (claquage). The method is used to increase the density of a plastically deformable material,and the volume of the treated mass where the plastic deformation limit is reached.
7.3.3.1.2 Controlled displacement grouting can be employed to strengthen the ground under existingstructures.
7.3.3.2 Hydraulic fracturing
7.3.3.2.1 Grouting by hydraulic fracturing is used to:
reinforce or stabilize the ground (soil or rock);
produce controlled uplift of structures;
achieve watertightness by creating compartments.
7.3.3.2.2 It is difficult to control the propagation of an hydraulic fracture plane. Hence, the grouting objectiveshould usually be achieved by an incremental series of injections, spread over a period of time.
7.3.3.3 Compaction grouting
7.3.3.3.1 Compaction grouting refers to the intrusion of a comparatively stiff (viscous) particulate grout intothe ground to induce displacement and deformation. The grout is usually extruded from open-ended injectiontubes. The grout consistency is such that the grout remains as a homogeneous mass and neither permeationnor hydraulic fracturing of the host medium occurs. Compaction grouting is most often used to compact anddensify loose ground and to raise and support structures which have settled.
7.3.3.3.2 The final grid of grout holes is generally defined during the grouting process, in accordance with theresults of control tests performed in the centre of the primary grid.
7.3.3.3.3 The slow dissipation of pore pressure in low permeable ground shall be taken into account for thecontrol measures.
7.4 Grout
7.4.1 Type and composition
7.4.1.1 The type and composition of the grout shall be selected according to the ground conditions andspecifications of the works.
7.4.1.2 The national standards shall be consulted for restrictions in the use of specific types of grouts.
7.4.2 General considerations
7.4.2.1 In order to achieve the performance specifications for grouting works the design shall consider:
the purpose of the treatment;
grout placement, timing and sequencing;
environmental conditions;
rheological properties of the grout and their change with time, such as the water content of the solidconstituents of a grout mix;
setting and hardening time of the grout;
the compatibility of the grout with the components of the delivery system and the ground;
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physical properties after setting;
the effects of syneresis on the mechanical stability of the injected ground (for silicate based grouts).
7.4.2.2 The following environmental conditions shall be considered for the design:
the size of openings to be filled by the grout and the size of the solid (hydrated) grout constituents,particularly the sizes of the pore necks (smallest access area) rather than the porosity;
the permeability of the medium to be injected and the penetrability of the grout;
the chemistry of the groundwater, mix water, and the ground;
ground and grout temperature;
the risk and effect of grout drying out upon exposure;
the environmental impact during mixing, processing and the placement of the grout;
the pollution potential of the grout.
7.4.2.3 If permeation grouting is to be undertaken, the dimensions of interconnected voids in the soil(effective porosity) or interconnected fissures in rock, should be known before designing the grout. This isparticularly relevant for suspensions, where the filter criteria (relating particle size to void opening) and thestability of the mix under in situ gradients should be investigated. The cohesion of the mix should further berelated to the desired reach of the treatment, and the viscosity of the grout to the permissible working pressures.
7.4.2.4 The determination of the setting time depends on:
the volume of grout to be prepared and injected;
the ground permeability;
the interconnected porosity of the ground;
the rate of groundwater flow;
the time of injection for one pass;
the anticipated placement time of a prepared batch of grout.
7.4.3 Parameters and criteria
7.4.3.1 The execution design shall state the range and median values of the following grout parameters forgiven environmental conditions:
density, viscosity, yield or cohesion;
shear and compressive strength;
particle size of cement or binder;
water retention capacity;
for silicate gels the relative percentage of the reagent and silicate (neutralization rate);
sedimentation rate.
7.4.3.2 Table A.1 presents the measuring conditions for the main parameters of each class of grout.
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7.4.3.3 The design should further specify criteria for the selection of a specific mix if different mixes havebeen suggested, and the permitted maximum and minimum grout temperatures during processing andplacement.
7.4.3.4 In soils, a groutability ratio, such as the D10/d90 or D15/d85 criterion, can be used to assess thepenetrability of particulate grouts (see glossary, annex B). In rock, the maximum particle size to fissure width isconsidered (a ratio of three is commonly used).
7.4.3.5 Limit criteria for changing the mix design should be decided upon at the outset of the works for thecase that:
grout takes are significantly in excess of those anticipated in the design;
no grout acceptance can be achieved with the design mix;
undesirable ground movement occurs.
7.4.4 Applicability
7.4.4.1 The types of grout applicable for different types of ground are shown in Table 3.
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Table 3 Indicative grouts for different types of groundHost
mediumRange Non-displacement grouting Displacement
groutingPermeation Fissure or
contactgrouting
Bulk filling
Gravel, coarse sand andsandy gravelK> 5 10-3 m/s
Pure cementsuspensions,Cement basedsuspensions
Granular soil Sand5 10-5
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the grout rheology.
7.5.1.3 The design should indicate how to adapt Q, V and P for a given mix design, or the rheology of themix design, to the anticipated ground response during grout placement.
7.5.1.4 For permeation, the flow (injection) rate Q should be controlled to ensure that the effective pressureremains lower than the ground fracturing pressure.
7.5.1.5 The effects of the modification of the pore water pressures induced by the treatment, and relatedchanges in the in situ stresses, should be considered.
7.5.2 Drilling pattern and borehole design
7.5.2.1 The relative positioning of injection points within the mass to be grouted depends on:
the shape of the mass;
physical constraints influencing the positioning of boreholes;
the expected directional tolerances of the boreholes;
an assessment of the expected distance of grout travel (radius of efficiency) within the host material.
7.5.2.2 The number, position, spacing, depth, diameter, inclination and orientation of boreholes andinjection points shall be based on geological conditions, the type of structure to be grouted, the results to beobtained, the grouting method and purpose, the type of grout to be used, injection pressure and rate of grouttake. The design shall make adequate provision for any variation in the above parameters.
7.5.2.3 Whenever possible, the design should be refined by conducting site grouting trials.
7.5.2.4 The positions of all foreseen injection boreholes shall be indicated on a plan and they shall benumbered.
7.5.2.5 When impregnating a rock the spatial relationship between bedding planes and joints or fracturesshall be taken into account. The boreholes shall be adjusted to the orientation and separation of the principalopen features.
7.5.2.6 The grout hole diameter should be based upon the type and condition of the rock to be grouted andthe depth and inclination of the hole. It should be chosen to allow any foreseen in-hole tests.
7.5.2.7 Care should be taken to minimize borehole deviations and the design should adjust the spacingbetween holes to compensate for the deviations expected. In general, the borehole axis should notdeviate from the planned orientation by more than 3 % for lengths of less than 20 m. In the case oflonger holes the spacing between neighbouring holes should be adjusted to compensate fordeviations.
7.5.3 Grouting sequence
7.5.3.1 In its simplest form, a sequence constitutes a single grout type introduced through a single hole.
7.5.3.2 The grout placement sequence may progress to multiple stages, over many holes, with each stagerequiring a sequence of injection passes of differing grout types.
7.5.3.3 The design shall therefore specify the following variables:
the manner in which the treatment will progress through the mass being grouted (inwards or outwards,top-down or bottom-up, etc.);
the number of grouting phases;
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the number of passes per stage;
the type of grout introduced for each pass.
7.5.4 Grouting pressure
7.5.4.1 In general practice, the grouting pressure is measured at the grout delivery pump and/or at the holecollar. However, variations in hydraulic head, and friction losses in the delivery system, will result in this 'workingpressure' being different from the 'effective pressure' acting in the ground.
7.5.4.2 In rock, the value of the 'effective grouting pressure' can be assessed in relation to the pressure atwhich:
the rock breaks under tension;
predominantly horizontal planes in the rock are parted, and displacement occurs; or
widening of the treated fissures takes place.
7.5.4.3 During non-displacement grouting of soils, the effective (or limit) grouting pressure is dependent onthe confining pressure at the point of injection.
7.5.4.4 For non-displacement grouting, the permissible injection pressure is the maximum pressure atwhich a grout is allowed to be introduced into the ground in order to avoid any undesirable deformation of theground.
7.5.4.5 In non-displacement grouting, a value for the permissible injection pressure shall be given in thedesign.
7.6 Monitoring and control criteria
7.6.1 The design shall specify the monitoring and control criteria before, during and after the grouting worksand shall indicate which of the following parameters to monitor and control and how this is to be done:
the grout properties during processing and placement;
the tolerances in direction and inclination of boreholes (drilling accuracy);
the criteria for ending injection after each pass;
the results achieved after each phase of grouting and/or at the end of the project;
ground movement or deformations;
chemistry of water;
water levels in existing wells or observation boreholes.
7.6.2 The criteria for ending an injection pass should be based on the following:
in soil:
limiting pressure and/or volume;
ground movement due to grouting exceeding a limit value;
escape of grout to surface, into buildings or neighbouring holes;
bypassing of packers;
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in rock:
limit pressure (refusal) and/or volume;
ground movement;
escape of grout;
unacceptable loss of grout into adjoining areas.
7.6.3 The design shall specify the control criteria and the tests necessary to verify that the objectives of thegrouting works are achieved.
8 Execution
8.1 General
8.1.1 Grouting works shall be staffed with qualified personnel. All key personnel shall have prior groutingexperience.
8.1.2 The equipment required to perform a grouting operation includes:
drilling and driving equipment;
mixing and proportioning equipment;
pumping equipment;
injection piping;
packers;
monitoring and testing equipment.
8.1.3 The equipment used for grout processing shall safely withstand the anticipated maximum groutingpressures.
8.1.4 Competent personnel shall maintain the grouting equipment for the duration of the works.
8.2 Drilling
8.2.1 The following drilling methods may be employed:
rotational drilling;
percussion drilling using either an external or down-the-hole hammer;
cased percussion drilling;
grab-, chisel- and bailer borings;
driving of lances;
vibrating of casing or drill pipes.
In unstable ground full borehole penetration may require:
the use of drilling muds, grouts or foams;
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temporary casing;
direct insertion of sleeve pipes;
progressive stabilization as the borehole advances.
If artesian conditions are expected counter-pressure drilling may be required.
8.2.2 Flushing media and drilling techniques shall be chosen so as not to impede the success of anysubsequent grouting operation (particularly regarding changes in permeability at the point of injection).
8.2.3 Local adjustments to the angles, orientation, and spacing of grout holes should be made as necessary.New holes should replace holes that are prematurely plugged and holes that show unacceptable boreholedeviation.
8.2.4 In open holes, if grouting does not follow immediately after cleaning, the hole collar should be protectedto avoid borehole contamination.
8.2.5 After drilling, open boreholes in rock shall be flushed in order to remove detritus and loose material, andto open cracks and fissures. This treatment shall not be applied in the case that the rock might be adverselyaffected by the flushing medium.
8.3 Grout preparation
8.3.1 Storage
Stored grout components shall be protected from the weather (especially temperature and humidity).
8.3.2 Batching and mixing
8.3.2.1 Contamination of the grout and its constituents shall be avoided during storage, handling anddelivery.
8.3.2.2 The storage containers (tanks) for ready-mixed grout shall ensure that the rheological or otherproperties of the grout are not unduly altered during storage.
8.3.2.3 Containment vessels for chemical grouts shall consist of materials that do not react with thechemicals used.
8.3.2.4 For grouts containing bentonite, the bentonite should be hydrated before introducing the binders.
8.3.2.5 The proportioning of grout components shall be carried out with calibrated measuring devices inaccordance with tolerances specified for the works.
8.3.2.6 Mixers shall be selected to ensure the homogeneity of the mix.
8.3.2.7 In order to allow uninterrupted delivery of particulate grouts, an intermediate holding tank should belocated between the mixing tanks and the pump(s). The mix in the holding tank should be agitated to preventseparation and/or premature setting.
8.3.2.8 Grouts with a fast setting time should be mixed as close as possible to the point of injection.
8.3.3 Pumping and delivery
8.3.3.1 The grout pumps and injection systems shall be chosen in accordance with the intended injectiontechnique.
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8.3.3.2 The following should be considered when selecting injection pumps:
an adjustable rate of grout delivery;
outputs which permit sufficient volume of grout to be injected or pressure to be achieved within a givenperiod of time;
regulation of the injection velocity;
low-wear pumps (e.g. plunger pumps) for abrasive grouts;
ease of cleaning and maintenance;
valve diameters which are able to accommodate the viscosity of the injected material.
8.3.3.3 The injection pressure should be measured as close to the point of placement as is practicable.
8.3.3.4 The injection systems shall dampen pressures surges to minimize the risk of unintended andundetected initiation of hydraulic fractures.
8.3.3.5 If the grout preparation plant is remote from the point of injection, an intermediate relay stationshould be considered.
8.3.3.6 Grout delivery lines (pipes) shall resist the maximum anticipated pump pressure with an adequatefactor of safety. Their diameter shall permit flow rates high enough to avoid separation of the mixed groutcomponents (suspensions).
8.3.3.7 If using sleeve pipes, the interior of the injection tube should be washed at the end of each injectionphase.
8.3.3.8 Suspensions shall be agitated until injection of the grout in order to prevent sedimentation.Solutions which tend to separate shall be agitated until injection.
8.3.3.9 At low injection rates, a return flow system should be used to avoid sedimentation.
8.4 Grout placement
8.4.1 The method of grout placement will be determined by the ground condition, the works requirement andthe type of grout used. The basic approaches are the following:
a) injection in unsupported boreholes in stable ground;
b) injection via sleeve pipes previously placed in a temporarily cased borehole, in unstable ground;
c) injection through the drill string in unstable ground, generally considered as a pre-grouting phase and to befollowed by approaches a) or b);
d) compaction grouting is usually performed through a casing retrieved during upstage grouting.
The general implementation in soil and rock is summarized in Table 4 where a stage is defined as apredetermined length of injection bounded either by a double packer, or by a single packer and the base of thehole.
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Table 4 Grouting strategies
ROCK
Stable Unstable
SOIL
Open hole Sleeve pipe Drill rod Sleeve pipe Lance or casing
single stage X X X X
multi-stage X X
ascending stage X X X X X X
descending stage X X X X
8.4.2 Soil grouting can be achieved with casing, grout sheath, pierced casing, and sleeve pipes.
8.4.3 Sleeve pipes which are permanently sealed into the ground by use of a support mix (sleeve grout) allowa repeated use of the injection points.
8.4.4 When grouting in soils, adjacent sleeve pipes should be flushed as a precaution against grout leakage.
8.4.5 Large openings (voids, cavities, etc.) are generally filled under gravity, either directly, or via a tremiepipe extending to the base of the opening.
8.4.6 Packers are used to isolate a grouting stage. Packers are either passive, mechanical or pneumatic, andhave to be long enough to minimize the risk of grout bypass through the medium being grouted.
8.4.7 Packers shall ensure tight sealing between the grout hole wall and the injection pipe at maximumgrouting pressure.
8.4.8 In instances where the grout has a tendency to bypass the packers, especially in ascending stagegrouting, a flushing system should be installed to wash out bypassing grout.
8.4.9 The maximum stage length in rock should normally not exceed 10 m. In intensely fissured or disturbedrock this length should be adjusted accordingly. Injection stages in soil should not exceed 1 m in length.
8.4.10 When grouting in suspected or known conditions of flowing groundwater, excessive dilution or completeloss of grout should be prevented. Depending on the ground conditions, the purpose to be achieved and therate of groundwater flow, the following precautions should be taken:
the use of a grout with a short setting time, even a flash setting time (such as aquareactive resins, cementbased grout with sodium silicate);
the use of a viscous grout or/and grout with a high dry matter content;
the use of additives to limit grout dilution.
8.4.11 If using suspensions when grouting in absorbent rock, a water retaining grout should be chosen.
8.4.12 Injection parameters (pressure, volume and flow rate) shall be adjusted to avoid unacceptabledeformation and displacement of the ground, unless this is specifically intended. Particular caution shall betaken in the vicinity of sensitive structures.
8.4.13 The flow rate for permeation grouting depends on the size of the interstices and the viscosity of thegrout.
8.4.14 During the placement and handling of grouts and grout components, precautions shall be taken to avoidspillage and, in particular to prevent the escape of any liquid or grout off-site.
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8.5 Grouting sequences
8.5.1 The planning of grouting works is an interactive, on going process requiring on-site management.Decisions concerning changes in treatment or in parameters set out in the design and defined in the methodstatement, as well as continuation or termination of the grouting operation, shall be taken by all concernedparties.
8.5.2 Descending or downstage grouting is commonly reserved for the treatment of unstable rock. If severalholes are grouted using downstage grouting, the uppermost stage in all holes is drilled and grouted beforedrilling and grouting the next stage in all neighbouring holes.
Upstage grouting is only used in open holes in stable rock or if the aim is compaction grouting.
Multistage grouting, using sleeve pipes is generally used in soils and sometimes in unstable rock.
Combinations of these techniques are possible.
8.5.3 The split-spacing method of first drilling and grouting primary holes, followed by intermediate secondaryand finally tertiary or even quaternary holes may be used to provide a minimal uniform coverage and to allow forcloser spaced holes to be restricted to those areas where progressive experience shows them to be necessary.
8.5.4 The spacing of the primary injection holes shall be decided upon on the basis of experience or groutingtests.
8.5.5 When using the split-spacing method, selected primary hole should be grouted first as exploratory groutholes except in areas of previous test grouting to:
allow for better description of the geological and hydrogeological situation;
permit the final selection of the grout hole depth for the remaining primary holes.
8.5.6 In order to limit the lateral migration of grout beyond the designated treatment area, injections shouldcommence on the perimeter of the zone to be treated and move progressively inward. This procedure shouldnot be used if there is a danger of groundwater entrapment or if the aim is to drive water out of the treatmentzone.
9 Execution supervision and control
9.1 General
9.1.1 The supervision of the grouting process shall be based on the design specifications. The supervisionprocedure shall provide documentation based on detailed observation of each phase of the operation. Thedocumentation shall form the basis for any modifications to the design specifications.
9.1.2 During construction, the design assumptions shall be verified according to the data acquired and, ifnecessary, modified.
9.2 Supervision
9.2.1 All grouting work should be supervised by suitably experienced representatives from all concernedparties.
9.2.2 Prior grouting experience shall be required of all key personnel.
9.2.3 The execution of the works shall be supervised continuously and all observations made shall becompared with the design parameters and assumptions. If the observations differ significantly from the design,then the reason for deviation shall be investigated and the design or execution parameters adjusted to thesenew conditions.
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9.2.4 The designers shall participate in the decision when specification adjustments are made.
9.2.5 The supervision of grouting sites should be facilitated by automating the mixing and delivery systemsand installing mechanical, analogue or, preferably, computerized recording devices for real time monitoring andcontrol of the grout placement parameters.
9.2.6 Records shall be kept during the entire field operation, showing all data pertaining to each phase of thework.
9.2.7 Comprehensive records covering each phase of the work should be incorporated in a final report.
9.3 Monitoring and control
9.3.1 General
9.3.1.1 Prior to commencing work, a location and condition survey should be conducted on any structuresand utilities likely to fall within the grout influence zone. Further surveys should be made as grouting proceeds.
9.3.1.2 The type, extent and accuracy of monitoring requirements on and off-site shall be clearlyestablished in project documents and before work commences on site.
9.3.1.3 Computerized systems should be used to:
monitor the drilling of boreholes;
measure, control and interpret the drilling parameters;
measure and control the grouting parameters of the different grouts injected in each grouting stage.
9.3.1.4 The parameters, which should be monitored, recorded and analysed during the grouting process,vary continually with time. Hence, the grouting process should be monitored and preferably controlled by adatalogger or field computer to follow in real-time the grouting parameters.
9.3.1.5 Computerized information control should provide hard copy print-outs or back up copies whichshould be stored in a safe place.
9.3.1.6 Monitoring and control measurements should be carried out, according to the project requirements(design).
9.3.1.7 When data loggers or field computers are used on site, the data sampling intervals should bechosen according to the project requirements.
9.3.1.8 To determine the success of grouting, appropriate (specified) control tests should be carried out atthe earliest practical time in order to react as soon as possible to anomalies.
9.3.1.9 The relative development of the injection pressures, the quantity injected and the flow rate with timeshould be recorded for each grouting phase and for ongoing comparison as the work progresses.
9.3.2 Environmental impact
9.3.2.1 Any environmental impact assessment and especially the decision regarding admissible limitsshould be based on two largely independent investigations:
the status quo should be assessed prior to starting any work, with particular attention paid to groundwaterconditions (chemistry, velocity and direction of groundwater flow, existing and planned use of groundwaterand distance between withdrawal points);
the expected polluting effect of the grout and the duration of pollution (in case of transitory effects lessstringent levels are applicable) should be determined, distinguishing between gaseous, liquid and solidstate.
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9.3.3 Control of objective
9.3.3.1 The control methods chosen shall depend on the aim of the treatment.
9.3.3.2 Tests should be conducted both before and after grouting to provide an indication of the groutingsuccess.
9.3.3.3 Test may include permeability tests, mechanical tests in the field and the laboratory, excavation,etc.
9.3.3.4 The choice of permeability test depends on the ground condition, and degree of sophisticationrequired. Rising head or falling head (Lefranc) tests are often conducted in granular soils. Lugeon tests areperformed in rock. Large scale pumping or injection tests can determine the regional permeability for a largebody of soil or rock.
9.3.3.5 The data recorded during drilling may be used to check whether the objectives are being met.
9.3.4 Monitoring of displacement
9.3.4.1 Appropriate instrumentation should be installed that will be capable of monitoring ground and/orstructural movements with sufficient accuracy to ensure that they will remain within the established tolerancelimits.
9.3.4.2 (Where required, instrumentation for movement monitoring shall be installed sufficiently in advanceof the grouting work to allow the identification of background influences (temperature variations, groundwaterfluctuation, etc.), and thereby to compensate for their effect on future readings.
9.3.5 Drilling
9.3.5.1 During drilling, a number of parameters may be recorded automatically:
rate of penetration;
fluid pressure;
flow rate;
reflected energy;
rotational speed;
torque;
pull down force;
borehole length.
The interpretation of recorded parameters provides useful information with regard to geological andgeotechnical variations.
9.3.6 Grout
9.3.6.1 The quality and consistency of the grout shall be maintained by conducting control tests whichmonitor the ongoing compliance with the required characteristics.
9.3.6.2 The granulometry of microfine suspensions should be controlled and monitored, taking flocculationinto account.
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9.3.6.3 On site, the grouts shall be subjected to at least the routine control tests given in Table 5.
Table 5 Grout control tests
Suspensions Microfine suspensions Solutions (chemical grout) Mortars
Density Density Density Density
Marsh viscosity Grainsize/sand columntests
Setting time Workability
Setting time Viscosity
Bleeding Bleeding
In hardened particulate grouts the compressive strength and/or shear strength shall be tested. For testing, seealso Annex A.
9.3.6.4 The batching process shall be continuously monitored and recorded.
9.3.6.5 During grouting the grout components and the quantity prepared shall be monitored.
9.3.6.6 Trace indicators may be used on treated ground in order to assess the presence of grout.
10 Works documentation
10.1 The following documents should be available on site:
a geotechnical baseline report containing all the investigative data relevant to the establishment of a designfor the grouting works;
an organization chart which clearly defines the decision making responsibilities of the key personnelrepresenting all concerned parties;
a Method Statement which defines the objectives of the grouting work, details the procedures that will beemployed to achieve that objective, and proposes measurable criteria that will be used to establish theattainment of the objective. The Method Statement will be agreed upon by the responsible parties as abasis for commencing the work and contains:
a plan detailing all boreholes (plan view and sections), existing structures, geological formations, waterlevels, planned constructions and boundaries of treatment;
a document detailing the types of grout, the envisaged quantities of grout to be injected per grout stagein each borehole, the sequence of injection, maximum pressures and the injection rates expected;
documents concerned with monitoring on site, maintenance and further activities after handover of thegrouting works.
10.2 The following documents should be produced on site:
a daily record of observations concerning drilling and grouting;
a monthly record indicating the daily progress and the grout consumption;
a final report containing all pertinent technical and quantitative details;
a handover report on completion of the works in which the concerned parties confirm the attainment of theacceptance criteria defined in the Method Statement.
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10.3 The site reports shall mention:
general:
dates of activities;
drilling:
borehole (injection point) number and position, length, diameter, direction and inclination;
names of drillers;
drilling rig and method;
type of drilling fluid;
borehole equipment (e.g. casing, sleeve pipes, type of seal grout, etc.);
special observations during drilling or installation of equipment (e.g. fluid loss, unexpected loss of sealgrout);
mixing and injection:
grout compositions (types and mixing proportions) and characteristics;
grout volumes injected into the ground (consumption), pressure and duration for each pass;
interaction with other boreholes and observed leakage;
any unusual incidents and observations;
control:
sampling of the grout being used;
number of samples for laboratory;
routine quality controls;
names of personnel (and their qualification).
These records shall form the basis of grouting control.
10.4 A record of the ground surface levels shall be kept when necessary.
10.5 The grouting results should be summarized by graphical means and by statistical means whereappropriate (e.g. graphs of pressure against time).
10.6 Special events and decisions taken both during drilling and injection shall be recorded in field log books.
10.7 Grouting reports shall be prepared on site and signed by the responsible site engineer or hisrepresentative.
11 Special aspects (environment, site safety)
This chapter deals with those aspects of site safety and the protection of the environment which are specific togrouting operations. For general rules concerning site safety and protection of the environment, the relevantEuropean and National Standards shall be consulted/taken into account.
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11.1 Personnel safety
11.1.1 The safety of personnel and third parties is of prime importance.
11.1.2 The following potential problems should be considered when using grouts:
dust from powdered chemicals which are toxic to the skin, eyes or respiratory system;
fumes released from liquid grout mixtures;
grout components or grouts which are harmful on contact with the skin;
contamination of groundwater;
mixing of chemicals which can cause explosion;
disposal of refuse or waste water.
11.1.3 For all grouting works, protective clothing and gloves shall be worn at all times since most chemicalgrouts contain some components which are toxic to the skin. Face masks shall be available for workmen whowork in closed areas where fumes from grouts or dust from grout components may be breathed. Protectiveheadgear shall be available for all workmen at the site. Safety goggles shall be available for workmen in areaswhere grout is being injected.
11.1.4 Large batches of epoxy or polyester resins often generate significant amounts of heat and shouldtherefore be handled with care.
11.2 Environmental protection
11.2.1 Environmental impact, particularly the toxicity of the grout and the grout components and their effect onthe ground- and drinking water should be considered before grouting.
11.2.2 When testing the grouting material for environmental impact, the following aspects should beconsidered:
whether during processing, transport or grouting, substances can be generated or released which could behazardous to the environment or the grouting crew;
whether noxious substances can spread upon mixing with ground water;
whether reaction products can be produced or released which influence the water quality;
the type of particles eroded from hardened grout;
chemical reactions between hardened grout and the ground water.
11.2.3 Environmental impact risks on site include:
induced ground movement;
changes of groundwater level;
spreading of grout;
pollution of groundwater;
arial distribution (dust).
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11.2.4 Arrangements for disposal of excess grout should be made before the grouting operation begins.Advance consideration should also be given to:
ventilation in confined spaces;
catchtrays below grout pumps;
isolation of flammable materials;
used water collection.
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Annex A (informative)
Measurement of grout parameters
Table A.1 presents the measuring conditions, measuring devices, test procedures and units for measuring theprincipal grout parameters.
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Table A.1 Measurement of grout parameters
Parameter Unit Measuring apparatus/method Application Solution Suspension Mortar Remark1 Outflow time
(Cone viscosity)[s] Marsh cone (funnel diameter = 4,75 mm),
Other flow cones (diameter = 8, 10, 12 mm)lab and site N/A A A see R1
2 Viscosity (dynamic or apparent) [Pas] Coaxial viscometerRheometers
lablab and site
A A N/A see R1andR2
3 Density [kg/m3] PycnometerBeakerBarod mud balance
lab and site A A A
4 Cohesion, Yield, Shear strength [Pa] Coaxial viscometer, Rheometer,Plate cohesion meter,Kasumeter, Shearometer
lablab and site
N/A A N/A see R4
5 Water retention capacity [m3] Barod filter press (low pressure) lab and site N/A A A6 Bleeding rate, Sedimentation [%] or [m3/m3] for 2 hr Measuring cylinder lab and site N/A A A see R67 Workability [mm] Abrams cone lab and site N/A N/A A see R78 Setting time [s] Overturned glass beaker, Vicat needle lab and site A A A see R89 Hardening time [s] Vane test
Shear box,Unconfined compression test
lab and site A A A see R9
10 HardeningDeformationFinal strength
Unconfined compression test withstress-strain record,Triaxial test, Point load tests
lab A A A see R10
11 Durability Mechanical: flow testChemical
A A A see R11
12 Thixotropy Rheometer, Viscometer, Hydrometer lab N/A A N/A see R1213 Syneresis [Vol %] Volume of water expelled from sample with
timelab A N/A N/A see R13
14 Shrinkage/expansion [%] of vol, length Shrinkage limit determination lab and site A A A see R1415 Granulometry Particle size measurement lab and site N/A A A see R1516 Penetrability Grouting test
Sand column testsitelab
A A N/A see R16
N/A = not applicable/not generally used, A = applicable
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